President Reagan's children famously disagreed with him — and each other — during their lives in and out of the spotlight. On one thing, though, they are unanimous: If their father were alive on his 100th birthday on Feb. 6, he would skip the party to watch the Super Bowl. The college football star would not have let anything interfere with his passion for the game.

"If he were here, he would not be at any of the celebrations for himself. He'd be watching the Super Bowl," says daughter Patti Davis, 58. "I can promise you that."

The century since Reagan's birth in the small town of Tampico, Ill., spans enormous change, says his son Ron.

"It's nearly the period of the greatest change ever anywhere on the planet, and he just happened to be around for the whole thing. In a sense, he was born at the tail end of the 19th century," Ron, 52, says.

The younger Reagan investigates his father's early life and his family's roots in Ireland in a book published this month: My Father at 100. Pictures of Tampico at the time of Reagan's birth show "a street that's dirt, there's not a car in sight. … This is the world he was born into," his son says. "He ended up ending the Cold War and in control of a nuclear arsenal. That's quite a journey."

A constant presence

Reagan's shadow, like that of most fathers, was a big one for his children, but the family drama played out in public from the time Reagan became a national political figure in the 1960s. The children from Reagan's first marriage, to actress Jane Wyman— Maureen, who died of cancer in 2001 at age 60, and Michael — sided with their father politically. "I was a Republican before he was," Maureen once said of her father, who left the Democratic Party in the early 1960s. She worked for Reagan's campaigns as much as she was allowed to. Michael, 65 and until recently a conservative talk radio host, has written his own book for Reagan's centennial: The New Reagan Revolution: How Ronald Reagan's Principles Can Restore America's Greatness.

Patti and Ron, the children of Reagan and his second wife, Nancy, established themselves as politically and socially liberal, to the dismay of their parents.

"I truly didn't agree with the political slant that I heard around the dinner table growing up," says Davis, a writer who lives in Los Angeles. She posed nude for Playboy, lived with a boyfriend without being married and wrote semi-autobiographical novels that were not flattering of her parents. "The way I acted out those disagreements … had a lot to do with getting my father's attention. Maureen was the good daughter, and she also was earnestly in agreement with my father (politically). … We both desperately wanted more of our father's attention."

When he was 12, Ron Reagan upset his parents by announcing he did not believe in God and would not be going to church. Later, he angered them by getting kicked out of boarding school.

"I don't think I was just doing this to be rebellious," he says now. "I was just one of those kids who was easily bored, spent much of the time daydreaming, wasn't interested in what I wasn't interested in."

Memories of the man

The years since Reagan's death in 2004 have allowed the difficult years when Reagan was stricken with Alzheimer's disease to recede, says Davis, who grew close again to her parents before Reagan's final illness. Now, she focuses on remembering "the parts of him that I think were so commendable: his graciousness to other people, his humanity, his kindness.

"When I think of him now, I don't think of him lying in that bed, even though the last three years of his life that's where he was. … He comes to me younger, he comes to me riding horseback, he comes to me working on the ranch or swimming out in the ocean. Nor does he come to me in the Oval Office. He's always in riding clothes or a bathing suit."

To son Ron, the image of his father that rings most true is of the lifeguard on the Rock River who saved 77 people from drowning. It combines Reagan's intense desire to make the world better and safer with his innate isolation. "He got to be the hero, but he got to be alone," his son says.

The Reagan kids also share an irritation with political candidates who obviously strive to emulate Reagan — or who claim they know what he would think.

"He's just not here anymore, and he can't speak for himself," says Ron, who as a commentator on cable network MSNBC had more than one fierce argument with someone who claimed to know what Reagan would have thought of a political situation. Many of those who say they know what Reagan thought "have not met him, let alone knew him."

"Everybody wants to be, 'I'm the next Ronald Reagan,' " Michael Reagan says. "The (Republican) Party does a disservice to itself trying to find the next Ronald Reagan. We ought to just be happy we had a Ronald Reagan in our lifetimes."

The rise of the Bush administration and the Tea Party has made both parties re-evaluate Reagan, his younger son says.

"He really did want to do good for people. He had lapses and blind spots. But he was not a venal person," Ron Reagan says. "The few times when he had to kind of tap-dance as president, you could always tell. Or I could. He was a lousy liar."

Ron cited his father's role in the Iran-contra scandal, which involved the secret sale of weapons to Iran in exchange for the release of U.S. hostages in Lebanon. Proceeds from the sale were used to support anti-communist rebels, or contras, in Nicaragua. Reagan had denied knowledge of the scheme to aid the rebels.

But Ron Reagan has concluded that Alzheimer's was affecting President Reagan before he left office. "That nanosecond hesistation that didn't used to be there … it was worrisome to me. I didn't know what was going on, but I felt something was not quite right here," he said. "Knowing what we now know about Alzheimer's disease, there should be no surprise." The president was diagnosed in 1994, so "he certainly had it in 1984," Ron Reagan says. "It takes that long to develop."

Reagan's children agree that the "mean-spiritedness," Davis calls it, of today's politics would dismay their father. Ron believes he would be "appalled" at repeated questions about President Obama's birth certificate, the socialist labels and other attacks. "He didn't like to see things get personal," Michael Reagan says.

Also lost is Reagan's folksy way of getting a point across. "If you really listen to my father, he spoke in parables" rather than in sound bites, his son says. "He told you a story. And he brought you into the story. … He didn't tell you the answer so much as you found it together."

Nancy Reagan, now 89, devotes much of her time to the Reagan library, her children say. "This whole 100th birthday thing is very, very meaningful to her," says Davis, who says she has lunch with her mother every Sunday. "She's so excited about it."

Son Ron says: "She's sharp as a tack. … She misses my dad, and she tells me that."

The siblings do not get together. If they have reconciled themselves to the difficulties of their famous father, they have not done so with one another. "Ronald Reagan was the glue that really kept this family together," Michael Reagan says. "When he died, the glue kind of died, too."

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